Metal product with excellent moldability surface-treated with alkali-soluble lubricant

ABSTRACT

A surface-lubricated metal product, with excellent shapability, comprising a metal having coated on both surfaces, or one surface, thereof an alkali-soluble lubricating film mainly comprising an alkali-soluble polyurethane aqueous composition containing a carboxyl group or a sulfonic acid group within the molecule, and a lubricating function-imparting agent in an amount of 1 to 30 mass % based on the alkali-soluble polyurethane aqueous composition, the film being coated to have a film thickness of 0.5 to 10 μm and the elastic modulus of the film after coating being 0.5 to 20 GPa at 25° C.

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a surface-lubricated metalproduct, with excellent shapability, which has an alkali-solublelubricating film on the surface.

BACKGROUND ART

[0002] In working, such as press shaping a metal sheet, a lubricatingoil or the like is usually coated so as to prevent the metal surface andthe metal mold surface from being scratched due to poor lubrication.However, the coating of a lubricating oil gives rise to a cumbersomeproduction process and the splashing of lubricating oil worsens theworking environment. Furthermore, in the degreasing step after pressshaping, the lubricating oil is removed using an organic halogen-basesolvent such as fluorocarbon, trichloroethane and dichloromethane, butthese solvents not only adversely affect the health of workers but alsothe majority thereof are a substance having an extremely high load onthe environment (They produce greenhouse effect gases which are ozonelayer-depleting substances and have global warming effects as high asseveral hundred to ten thousand times the effect of CO₂). Many of thesesolvents are chemicals which will be discontinued under the MontrealProtocol in view of protecting the ozone layer. In order to avoid use ofthese solvents, a substitute method is required.

[0003] Attempts are being made to dispense with degreasing by using avolatile lubricating oil or to perform degreasing using an organicsolvent. However, the volatile lubricating oil cannot give sufficientlyhigh shapability during severe press shaping and, when an organicsolvent is used, problems arise regarding safety. Also, a non-removingtype lubricating film of giving excellent shapability, corrosionresistance and solvent resistance without using a lubricating oil or asolvent for removing has been developed. However, the lubricating filmremains on the metal surface after the press shaping and, therefore,this technique cannot be used when the final product is required to havegloss or texture on the metal surface or when the worked product passesthrough a welding step. To solve this problem, a removing-typelubricating film which can be dissolved and removed in an alkalidegreasing step, after press shaping, has been developed. This alkaliremoving-type lubricating film is suitably used where a glossy metalsurface must be made available or a good welding property is requiredafter working.

[0004] Japanese Unexamined Patent Publications (Kokai) No. 8-156177, No.8-252887, No. 10-114014 and No. 10-88364 have proposed an alkaliremoving-type lubricating film using an acrylic resin. However, thealkali removing-type lubricating film using an acrylic resin sometimesfails in ensuring sufficiently high shapability and, for example,galling occurs under severe press shaping conditions such as deepdrawing and ironing. More specifically, when the press shaping isperformed without a coating of a lubricating oil, unless the elasticmodulus of the lubricating film coated on a metal is sufficiently high,the lubricating film is damaged due to pressure from the metal moldunder severe shaping conditions such as deep drawing or ironing (pressworking with a minus clearance), the metal mold and the surface of ametal to be worked adhere to induce mold galling and, as a result, thelubricating film peeled off at the galled part attaches to the metalmold or shaping failure such that impairment of the appearance of themetal surface is caused and these are a serious problem in the working.

[0005] An object of the present invention is to solve these problems andprovide an alkali soluble lubricant surface-treated metal product havingexcellent shapability.

DISCLOSURE OF THE INVENTION

[0006] The present inventors have made extensive investigations to solvethe above problems and to obtain an alkali soluble lubricantsurface-treated metal product having excellent shapability and, as aresult, have found that the above-described object can be attained whenboth surfaces or one surface of a metal are coated with analkali-soluble lubricating film mainly comprising a lubricatingfunction-imparting agent and an alkali-soluble polyurethane aqueouscomposition containing a carboxyl group or a sulfonic acid group withinthe molecule and where the elastic modulus of the film after coating is0.5 to 20 GPa at 25° C. The present invention has been accomplishedbased on this finding.

[0007] More specifically, the alkali soluble lubricant surface-treatedmetal product with excellent shapability, of the present invention, ischaracterized in that:

[0008] (1) an alkali-soluble lubricating film mainly comprising (A) analkali-soluble polyurethane aqueous composition containing a carboxylgroup or a sulfonic acid group within the molecule and (B) a lubricatingfunction-imparting agent in an amount of 1 to 30 mass % (wt %) based onthe alkali-soluble polyurethane aqueous composition is coated on bothsurfaces or one surface of a metal product to have a film thickness of0.5 to 10 μm and the elastic modulus of the film after coating is 0.5 to20 GPa at 25° C., wherein by coating this alkali-soluble lubricatingfilm, a metal product capable of exhibiting sufficiently highshapability even under severe press shaping conditions such as deepdrawing or ironing can be obtained;

[0009] (2) in the alkali soluble lubricant surface-treated metal productof the present invention, the alkali-soluble lubricating film mainlycomprises (A) an alkali-soluble polyurethane aqueous composition, (B) alubricating function-imparting agent in an amount of 1 to 30 mass %based on the alkali-soluble polyurethane aqueous composition and (C) asilica particle in an amount of 1 to 30 mass % based on the alkalisoluble polyurethane aqueous composition, wherein by adding the silicaparticle within the above-described range, the adhesion between thealkali-soluble lubricating film and the metal product surface isenhanced and the film strength of the alkali-soluble lubricating film isincreased and, as a result, the galling resistance is improved;

[0010] (3) in the alkali soluble lubricant surface-treated metal productof the present invention, the amount of the acid radical contained inthe alkali-soluble polyurethane aqueous composition (A) constituting thealkali-soluble lubricating film is from 30 to 180 in terms of the acidvalue wherein, by introducing a compound having an acid radical in anacid value of 30 to 180 in the polyurethane molecule, the coated filmcan have a flexibility capable of allowing shaping even under severeshaping conditions, despite the fact that the film after coating on ametal has a relatively high elastic modulus of 0.5 to 20 GPa at 25° C.;

[0011] (4) in the alkali soluble lubricant surface-treated metal productof the present invention, the neutralizer for the acid radical containedin the alkali-soluble polyurethane aqueous composition (A) forming thealkali-soluble lubricating film is sodium hydroxide or potassiumhydroxide, wherein by using sodium hydroxide or potassium hydroxide asthe neutralizer for the acid radical, the alkali solubility required inthe present invention can be achieved;

[0012] (5) in the alkali soluble lubricant surface-treated metal productof the present invention, the main component constituting thealkali-soluble polyurethane aqueous composition (A) forming thealkali-soluble lubricating film is a polyester polyol wherein, by usinga polyester polyol as the main component constituting the alkali-solublepolyurethane aqueous composition (A), the alkali solubility required inthe present invention can be achieved even at a low temperature such asroom temperature;

[0013] (6) in the alkali soluble lubricant surface-treated metal productof the present invention, the lubricating function-imparting agent (B)forming the alkali-soluble lubricating film comprises one or more memberselected from the group consisting of a polyolefin-base wax, aparaffin-base wax, a stearic acid-base solid lubricant and a waxcomprising a fluorine-containing resin wherein, by the addition of thislubricating function-imparting agent, a low dynamic friction coefficientcan be ensured over a wide temperature range and a good lubricatingfunction can be attained;

[0014] (7) in the alkali soluble lubricant surface-treated metal productof the present invention, the elastic modulus of the film after coatingis 0.5 to 6 GPa at 25° C. and, at the same time, the tensile elongationpercentage of the alkali-soluble polyurethane aqueous composition (A) asthe main component of the film exceeds 10%, or the elastic modulus ofthe film after coating exceeds 6 GPa at 25° C. and, at the same time,the tensile elongation percentage of the alkali-soluble polyurethaneaqueous composition (A) as the main component of the film is 10% or lesswherein, by having such a constitution, the film can be balanced in theelasticity and elongation and a metal product capable of exhibiting asufficiently high shapability even under severe press shaping conditionscan be provided;

[0015] (8) in the alkali soluble lubricant surface-treated metal productof the present invention, the glass transition temperature of thealkali-soluble polyurethane aqueous composition (A) in the coatedlubricating film is 100° C. or more wherein, although a steel sheetsurface sometimes reaches a temperature of 100° C. or more due tofrictional heat during working under severe press shaping conditions ofcontinuously performing deep drawing or ironing without using alubricating oil, the glass transition temperature of the alkali-solublepolyurethane aqueous composition, as a continuous phase in thelubricating film, is 100° C. or more and, therefore, even when the steelsheet surface reaches a temperature of 100° C. or more, the film doesnot decrease in elastic modulus and exhibits an excellent gallingresistance;

[0016] (9) in the alkali soluble lubricant surface-treated metal productof the present invention, the alkali-soluble lubricating film mainlycomprises (A) an alkali-soluble polyurethane aqueous compositioncontaining a carboxyl group or a sulfonic acid group within the moleculeand (B) a lubricating function-imparting agent in an amount of 1 to 30mass % based on the alkali-soluble polyurethane aqueous composition, themain component of the alkali-soluble polyurethane aqueous composition isa polyester polyol, the neutralizer for the acid radical contained inthe alkali-soluble polyurethane aqueous composition (A) is sodiumhydroxide or potassium hydroxide, the amount of the acid radicalcontained in the alkali-soluble polyurethane aqueous composition (A) isfrom 30 to 180 in terms of the acid value, the lubricatingfunction-imparting agent (B) comprises one or more member selected fromthe group consisting of a polyolefin-base wax, a paraffin-base wax, astearic acid-base solid lubricant and a wax comprising afluorine-containing resin, the alkali-soluble lubricating film is coatedon both surfaces or one surface of a metal to have a film thickness of0.5 to 10 μm, the elastic modulus of the film after coating is 0.5 to 6GPa at 25° C. and, at the same time, the tensile elongation percentageof the alkali-soluble polyurethane aqueous composition (A) as the maincomponent of the film exceeds 10%, or the elastic modulus of the filmafter coating exceeds 6 GPa at 25° C. and, at the same time, the tensileelongation percentage of the alkali-soluble polyurethane aqueouscomposition (A) as the main component of the film is 10% or less, andthe glass transition temperature of the alkali-soluble polyurethaneaqueous composition (A) is 100° C. or more, wherein the alkali solublelubricant surface-treated metal product maintains excellent shapabilityeven under severe press shaping such as deep drawing or ironing andshaping failures hardly occur; and

[0017] (10) the alkali soluble lubricant surface-treated metal productas described in (9) of the present invention may further comprise (C)silica particles in an amount of 1 to 30 mass % based on thealkali-soluble polyurethane aqueous composition, wherein by containingsilica particles, as such, the adhesion between the alkali-solublelubricating film and the metal product surface is enhanced and the filmstrength of the alkali-soluble lubricating film is increased and, as aresult, the galling resistance is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIGS. 1 to 3 are views for explaining the process of producingand using the alkali soluble lubricant surface-treated metal product ofthe present invention.

MODE FOR CARRYING OUT THE INVENTION

[0019] The present invention is described in detail below.

[0020] The present inventors have made extensive investigations on analkali soluble lubricant surface-treated metal product having a functionof exhibiting sufficiently high shapability under continuous shapingconditions and bringing about dissolution or desorption of thelubricating film in the alkali degreasing step after shaping and, as aresult, it has been found that this function is brought out when thefilm obtained after coating a coating material composition comprising analkali-soluble polyurethane aqueous composition and a lubricatingfunction-imparting agent on a metal surface has an elastic modulus of0.5 to 20 GPa at 25° C. (preferably, the elastic modulus of the filmafter coating is from 0.5 to 6 GPa at 25° C. and, at the same time, thetensile elongation percentage of the alkali-soluble polyurethane aqueouscomposition (A) as the main component of the film exceeds 10%, or theelastic modulus of the film after coating exceeds 6 GPa and at the sametime, the tensile elongation percentage of the alkali-solublepolyurethane aqueous composition (A) as the main component of the filmis 10% or less), the alkali-soluble polyurethane aqueous compositioncontains a carboxyl group or a sulfonic acid group within the moleculein the range from 30 to 180 in terms of the acid value, and sodiumhydroxide or potassium hydroxide is used as the neutralizer for theacid.

[0021] The alkali-soluble polyurethane aqueous composition for use inthe present invention can be obtained by reacting a compound having atleast two isocyanate groups per one molecule, a compound having at leasttwo active hydrogen groups per one molecule and a compound having atleast one or more active hydrogen group within the molecule andcontaining an acid radical such as carboxyl group or sulfonic acidgroup, and dissolving or dispersing the reactant in water.

[0022] Examples of the compound having at least two isocyanate groupsper one molecule for use in the present invention include aliphaticdiisocyanates such as trimethylene diisocyanate, tetramethylenediisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate,1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylenediisocyanate, 1,3-butylene diisocyanate, 2,4,4- or2,2,4-trimethylhexamethylene diisocyanate and 2,6-diisocyanatomethylcaproate; alicyclic diisocyanates such as 1,3-cyclopentane diisocyanate,1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate,3isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate,4,4′-methylenebis(cyclohexylisocyanate), methyl-2,4cyclohexanediisocyanate, methyl-2,6-cyclohexane diisocyanate,1,4-bis(isocyanatomethyl)cyclohexane, 1,3bis (isocyanatomethyl)cyclohexane and norbornene diisocyanate; aromatic diisocyanates such asm-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyldiisocyanate, 1,5-naphthalene diisocyanate, 4,4′-diphenylmethanediisocyanate, 2,4- or 2,6-tolylene diisocyanate or a mixture thereof,4,4′-toluidine diisocyanate, dianisidine diisocyanate and4,4′-diphenylether diisocyanate; and aroma-aliphatic diisocyanates suchas 1,3- or 1,4-xylylene diisocyanate or a mixture thereof,ω,ω′-diisocyanato-1,4-diethylbenzene, and 1,3- or1,4-bis(1-isocyanto-1-methylethyl)benzene or a mixture thereof. Thesevarious isocyanate group-containing compounds may be used, but anaromatic, aroma-aliphatic or aliphatic isocyanate compound is preferablyused and reacted so that the lubricating film after coating can have anelastic modulus of 0.5 to 20 GPa, mold galling can be prevented and asufficiently high shapability can be attained.

[0023] Examples of the compound having at least two active hydrogengroups per one molecule include compounds having an amino group, ahydroxyl group or a mercapto group as the group having active hydrogen,Among these, in view of the reaction rate with an isocyanate group andthe mechanical properties after coating, compounds having a hydroxygroup are preferred. Also, from the standpoint of good mechanicalproperties of the film, the number of functional groups in the compoundhaving active hydrogen groups is preferably from 2 to 6, more preferablyfrom 2 to 4. Furthermore, in view of the concentration of a urethanebond which affects the final film performance and also in view ofworkability in production, the molecular weight of the compound havingactive hydrogen groups is preferably from 200 to 10,000, more preferablyfrom 300 to 5,000.

[0024] Examples of the compound having a hydroxyl group as the activehydrogen group include a polyester polyol, a polyether polyol, apolyether ester polyol, a polyester amide polyol, an acrylpolyol, apolycarbonate polyol, a polyhydroxyalkane, a caster oil, a polyurethanepolyol, and a mixture thereof.

[0025] In addition to the above-described polyol, for the purpose ofadjusting the urethane group concentration to optimize the filmproperty, a low molecular weight polyol having a molecular weight of 62to 200 may be mixed. Specific examples of the low molecular weightpolyol include glycols for use in the production of a polyester polyol,such as ethylene glycol, propylene glycol, 1,3-propanediol,1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol,1,8-nonanediol, neopentyl glycol, 2-methylpentanediol,3-methylpentanediol, 3,3-dimethylolheptane,2,2,4-trimethyl-1,3-pentanediol, 2,4diethyl-1,5-pentanediol, diethyleneglycol, dipropylene glycol, 1,4-cyclohexanediol and1,4-cyclohexanedimethanol; and compounds such as glycerin,trimethylolpropane and pentaerythritol.

[0026] These various compounds having an active hydrogen group may beused, but for attaining alkali solubility at a low temperature such asroom temperature, a polyester polyol and a polyurethane polyolconstituted by a polyester polyol are preferred.

[0027] Examples of the compound having at least one or more activehydrogen group within the molecule and containing an acid group such ascarboxyl group or sulfonic acid group include sulfonic acid-containingcompounds, such as 2-oxyethanesulfonic acid, phenolsulfonic acid,sulfobenzoic acid, sulfosuccinic acid, 5-sulfoisophthalic acid,sulfanilic acid, 1,3-phenylenediamine-4,6-disulfonic acid and2,4-diaminotoluene-5-sulfonic acid, derivatives thereof and polyesterpolyols obtained by copolymerizing these compounds or derivatives;carboxyl group-containing compounds, such as 2,2-dimethylolpropionicacid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid,dioxymaleic acid, 2,6-dioxybenzoic acid and 3,4-diaminobenzoic acid,derivatives thereof and polyester polyols obtained by copolymerizingthese compounds or derivatives; and carboxyl group-containing compoundsobtained by reacting a compound having an anhydride group such as maleicanhydride, phthalic anhydride, succinic anhydride, trimellitic anhydrideand pyromellitic anhydride with a compound having an active hydrogengroup, and derivatives thereof.

[0028] A carboxyl group or a sulfonic acid group may be introduced intothe alkali-soluble polyurethane aqueous composition by copolymerizing atleast one or more of the above-described acid radical-containingcompounds during the production of a polyurethane prepolymer or reactingit in the chain elongation reaction. The acid group is introduced intothe polyurethane molecule in the acid value range of 30 to 180 whereby,despite the high elastic modulus of 0.5 to 20 GPa after coating on ametal surface, flexibility capable of allowing shaping, even undersevere shaping conditions, is imparted to the film.

[0029] In order to successfully dissolve or disperse the alkali-solublepolyurethane aqueous composition in water, a large number of carboxylgroups or sulfonic acid groups in the polyurethane aqueous compositionmust be neutralized. Examples of the neutralizer which can be usedinclude primary amines such as ammonia, methylamine, ethylamine,n-propylamine and n-butylamine, secondary amines such as dimethylamine,diethylamine and diisopropylamine, tertiary amines such astrimethylamine, triethylamine, triethanolamine, triisopropanolamine anddimethylethanolamine, and alkali metal hydrides such as sodium hydroxideand potassium hydroxide. These may be used individually or in acombination of two or more thereof. The neutralizer may be addeddirectly to the polyurethane prepolymer or added to water when theprepolymer is dissolved or dispersed in the water. The amount of theneutralizer added is preferably from 0.1 to 2.0 equivalent, morepreferably from 0.3 to 1.3 equivalent, to the hydrophilic group.

[0030] In order to attain the good alkali solubility required in thepresent invention, sodium hydroxide or potassium hydroxide is preferablycontained as the neutralizer. This is far of the following reasons. Whensodium hydroxide or sulfonium hydroxide is used as the neutralizer forthe carboxyl group (—COOH) or sulfonic acid group (—SO₃H) in thepolyurethane composition, the sodium ion or potassium ion becomes aneutralizing ion species of the carboxyl group or sulfonic acid groupand such an ion is not dissipated by volatilization even at the filmformation on a metal sheet but remains in the film as the neutralizingion species (for example, —COO⁻Na⁺ or —SO₃ ⁻K⁺) after the film isformed. When the surface-treated metal product is dipped in an alkalisolution, the sodium ion or potassium ion is readily dissociated and theionized carboxyl group (—COO⁻) or sulfonic acid group (—SO₃ ⁻) isimmediately hydrated and, as a result, the film is dissolved. Thus, thefilm can have good alkali solubility. On the other hand, in the case ofusing the above-described amines or the like as the neutralizer, aneutralizer such as an amine has a readily volatilized property and, dueto the conditions at the film formation on a metal sheet, theneutralizer is partially or entirely volatilized to return theneutralization part which is once neutralized by the neutralizer to thecarboxyl group or sulfonic acid group and, as a result, even when thesurface-treated metal product is dipped in an alkali, hydration scarcelyoccurs. Thus, the film fails to have a good alkali solubility, in somecases.

[0031] In order to more successfully dissolve or disperse thealkali-soluble polyurethane aqueous composition in water, a surfactantor the like may be used.

[0032] In synthesizing the above-described polyurethane prepolymer, anorganic solvent may also be used. In the case of using an organicsolvent, specific examples of the organic solvent include acetone,methyl ethyl ketone, ethyl acetate, acetonitrile andN-methylpyrrolidone. The amount of the organic solvent is preferably onthe order of 3 to 50 mass % based on the reaction raw materials.

[0033] The polyurethane prepolymer is dissolved or dispersed in waterusing a homogenizer, a mixer or the like. At this time, the temperatureis preferably from room temperature to about 70° C. so as to prevent theevaporation of the basic substance neutralizing the hydrophilic groupand ensure the workability. Furthermore, during the dispersion in amedium such as water, the concentration of the polyurethane aqueouscomposition is preferably from 10 to 50 mass % so as to not excessivelyincrease the viscosity and to maintain the storage stability.

[0034] Also, another chain elongating agent may be further reacted togive a high molecular weight. As the chain elongating agent, forexample, known polyamine compounds are used. Examples of known polyaminecompounds include diamines such as ethylenediamine, 1,2-propanediamine,1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine,isophoronediamine, 4,4′-dicyclohexylmethanediamine,3,3′-dimethyl-4,4′-dicyclohexylmethanediamine and1,4-cyclohexanediamine; polyamines such as diethylenetriamine,dipropylenetriamine, triethylenetetramine and tetraethylenepentamine;compounds having an amino group and a hydroxyl group, such ashydroxyethylhydrazine, hydroxyethyldiethylenetriamine,2-[(2-aminoethyl)amino]ethanol and 3-aminopropanediol; hydrazines; andacid hydrazides. These polyamine compounds can be used individually oras a mixture of two or more thereof.

[0035] In the alkali-soluble polyurethane aqueous composition of thepresent invention, a film forming aid, a leveling agent, a defoamingagent and a weather resistance stabilizer may be added, if desired.

[0036] The film of the alkali-soluble polyurethane aqueous compositionof the present invention is most efficiently solubilized and removed byalkali degreasing but may also be removed by using warm water or asolvent.

[0037] The lubricating function-imparting agent for use in the presentinvention has a function of reducing the coefficient of friction on thefilm surface and thereby further imparting lubricity to prevent moldgalling or the like and to improve the press workability and the drawingworkability. The lubricating function-imparting agent for use in thepresent invention is not particularly limited as long as it is aparticle mainly comprising (a) a solid lubricant or wax comprising along-chain aliphatic hydrocarbon and having no polar group, (b) a solidlubricant or wax having a long-chain aliphatic hydrocarbon group(long-chain alkyl group) and a polar group within one molecule or (c) asolid lubricant or wax comprising a fluorine-containing resin and it canbe stably and uniformly dispersed in an aqueous treating solution.Preferred examples of the lubricating function-imparting agent for usein the present invention include those comprising a polyolefin-base waxwith the hydrocarbon group having from 125 to 700 carbons, such aspolyethylene and polypropylene, or a paraffin with the hydrocarbon grouphaving from 32 to 72 carbons (microwax) as the component (a), a stearicacid-base solid lubricant as the component (b), or apolytetrafluoroethylene, a polychlorotrifluoroethylene, a polyvinylidenefluoride, a polyvinyl fluoride or the like as the component (c), andthose obtained by mixing or modifying one or more of these solidlubricants or waxes (a), (b) and (c).

[0038] Examples of the solid lubricant or wax (b) include a higheraliphatic alcohol with the hydrocarbon group having from 12 to 22carbons, such as cetyl alcohol and stearyl alcohol; a higher fatty acidwith the hydrocarbon group having from 13 to 17 carbons, such as stearicacid and 12-hydroxystearic acid; a metal soap comprising a divalentmetal and a higher fatty acid with the hydrocarbon group having from 12to 30 carbons, such as lead stearate, zinc stearate and calciumstearate; as the ester type, an ester of a higher fatty acid with thehydrocarbon group having from 13 to 17 carbons and another hydrocarbon,an ester of a higher aliphatic alcohol with the hydrocarbon group havingfrom 13 to 17 carbons and an aliphatic dicarboxylic acid or a fattyacid, and an ester of a polyhydric alcohol and a higher fatty acid, suchas glycerin tristearate and trimethylolpropane tristearate; as the fattyacid amide type, a monoamide or a bisamide of a higher fatty acid withthe hydrocarbon group having from 15 to 17 carbons, such as palmiticacid amide, stearic acid amide, oleic acid amide, ethylenebisstearoamide and methylene bisstearoamide; and as the waxes, a higherfatty acid wax with the hydrocarbon group having from 27 to 34 carbons,a wax comprising an ester of a higher fatty acid with the hydrocarbongroup having from 27 to 34 carbons and an aliphatic diol, and a polarpolyethylene wax with the hydrocarbon group having from 125 to 700carbons, such as wax where a carboxyl group is bonded at the terminal ofpolyethylene chain and an acid group such as hydroxyl group is bonded tosome place on the chain.

[0039] The average particle size of the particle-shape lubricatingfunction-imparting agent for use in the present invention is preferably10 μm or less. If the average particle size exceeds 10 μm, not only doesthe film lose continuity and uniformity to decrease the adhesion to thesubstrate steel sheet or the adhesive property of the coating materialand generate the peeling of the lubricating function-imparting agentbut, also, the coating material composition suffers from low storagestability. The average particle size of the lubricatingfunction-imparting agent is more preferably from 0.5 to 6 μm. The“average particle size” as used herein means “d50 (50% average particlesize)” obtained by plotting a relational curve between the particle sizeand the cumulative volume ratio and reading the particle size when thecumulative volume ratio is 50%. At this timer the measurement isperformed as follows. A laser ray is irradiated in the state whereparticles are dispersed in a solvent, and the interference fringegenerated is analyzed to determine d50 or the particle sizedistribution. In the measurement by the present inventors, a SALD-3000Smanufactured by Shimadzu Corporation was used. The “d50” can also bemeasured by a general-purpose measuring device of other companies, suchas a CILAS manufactured by CILAS and an LA manufactured by HoribaSeisakusho.

[0040] The amount of the lubricating function-imparting agent added isfrom 1 to 30 mass %, preferably from 5 to 20 mass %, based on the solidcontent of the polyurethane aqueous composition. If the amount added isless than 1%, the required lubricating effect cannot be obtained,whereas if it exceeds 30 mass %, problems arise, for example, the filmstrength decreases or the lubrication-imparting agent is desorbed.

[0041] In the case of improving the film strength and the adhesion tothe substrate surface, silica is added. The silica particle may be anysilica particle such as water-dispersible colloidal silica, groundsilica and vapor phase silica. On taking account of the workability offilm and the corrosion resistance, the primary particle size ispreferably from 2 to 30 nm and the secondary aggregated particle size ispreferably 100 nm or less. The amount of silica added is preferably from1 to 30 mass % based on the solid content of the alkali-solublepolyurethane aqueous composition. If the amount added is less than 1%, asufficiently high effect of improving the corrosion resistance is notobtained and a sufficiently strong adhesion to the lower layer is alsonot obtained. If the amount of silica added exceeds 30%, the filmelongation decreases and this causes a reduction in workability toreadily generate galling.

[0042] In addition to those components (A), (B) and (C), the lubricatingfilm coated on the surface-lubricated metal product of the presentinvention may contain, if desired, a pigment for imparting a designproperty, an electrically conducting additive for imparting electricalconductivity, a thickening agent, a defoaming agent, a dispersant, adesiccating agent, a stabilizer, an anti-skinning agent, an antifungal,an antiseptic, an anti-freezing agent, and the like, according to thepurpose within range which does not deteriorate the properties of film.

[0043] In the present invention, the elastic modulus of thealkali-soluble lubricating film formed on a metal surface is, as theelastic modulus after coating, from 0.5 to 20 GPa, preferably from 1.0to 10 GPa, at 25° C. If this elastic modulus is less than 0.5 GPa, thefilm is readily damaged under severe press shaping conditions such asdeep drawing or ironing and a sufficiently high shapability cannot beexpected, whereas if it exceeds 20 GPa, the film cannot maintain theflexibility capable of allowing shaping under severe shaping conditions.The “elastic modulus after coating” as used herein means a Young'smodulus obtained based on the Universal hardness testing specified inDIN50359 and the like. In the measurement by the present inventors, anultrafine hardness testing machine “FISHER SCOPE H-100” manufactured byFisher Instrument Co. was used, but the elastic modulus after coatingcan also be measured by a similar device by another company. A Vickersquadrangular pyramid-shaped diamond indenter is used and, to eliminatethe effect of the metal surface far harder than the film, the maximumpenetration depth of the indenter is set to ½ or less of the filmthickness.

[0044] Furthermore, in the present invention, it is preferred that theelastic modulus of the alkali-soluble lubricating film formed on a metalsurface is, as the elastic modulus after coating, from 0.5 to 6.0 GPa at25° C. and, at the same time, the tensile elongation percentage of thealkali-soluble polyurethane aqueous composition (A) exceeds 10%, or theelastic modulus after coating exceeds 6.0 GPa at 25° C. and, at the sametime, the tensile elongation percentage of the alkali-solublepolyurethane aqueous composition (A) is 10% or less, and it is morepreferred that the elastic modulus after coating is from 1.0 to 6.0 GPaat 25° C. and, at the same time, the tensile elongation percentage ofthe alkali-soluble polyurethane aqueous composition (A) exceeds 10%, orthe elastic modulus after coating is from more than 6.0 GPa to 10 GPa at25° C. and, at the same time, the tensile elongation percentage of thealkali-soluble polyurethane aqueous composition (A) is 10% or less. Ineither case, where the elastic modulus after coating is from 0.5 to 6.0GPa and the tensile elongation percentage of (A) is 10% or less or wherethe elastic modulus after coating is from more than 6.0 GPa to 20 GPaand the tensile elongation percentage of (A) exceeds 10%, the film lacksin the balance between elasticity and elongation, and a sufficientlyhigh shapability cannot be exerted.

[0045] In the present invention, the glass transition temperature of thealkali-soluble polyurethane aqueous composition (A) in thealkali-soluble lubricating film formed on a metal surface is preferably100° C. or more. Under severe press shaping conditions of continuouslyperforming deep drawing or ironing without using a lubricating oil, asteel sheet surface sometimes reaches a temperature of 100° C. or moredue to frictional heat during working In such a case, if the glasstransition temperature of the alkali-soluble polyurethane aqueouscomposition (A) forming a continuous phase in the lubricating film isless than 100° C., the elastic modulus of the lubricating film decreasesto induce mold galling and the lubricating film peeled at the galledpart adheres to the metal mold or measurement failures such asimpairment of the appearance on the meal surface are caused. The “glasstransition temperature” as used herein means a glass transitiontemperature determined from peaks on a DSC curve obtained using adifferential scanning calorimetry (DSC) device at a temperatureincreasing rate of 5.0 ° C./min in a dry nitrogen atmosphere.

[0046] The thickness of the lubricating film coated on thesurface-lubricated metal product of the present invention is from 0.5 to10 μm. If the thickness is less than 0.5 μm, the film pressed at theworking cannot prevent damage to the plating layer and in addition, dueto sliding, the required workability cannot be obtained. If thethickness exceeds 10 μm, peeled film dust increases at the shaping andthis requires frequent cleaning of the metal mold, giving rise toreduction in the productivity.

[0047] The lubricating resin film of the present invention is coated onboth front and back surfaces or one surface of a metal product accordingto the purpose. The lubricating film coated on the surface-lubricatedmetal product of the present invention can be formed by coating the filmusing a conventionally known method such as roll coater coating methodand spray method, and bake-drying it. In the present invention, toobtain higher corrosion resistance and a higher adhesive property, thesubstrate may be subjected to a phosphate treatment or a chromatetreatment. The chromate treatment may be any of an electrolysis-typechromate treatment, a reaction-type chromate treatment and acoating-type chromate treatment. The chromate film is preferably a filmformed by coating a chromate solution comprising a partially reducedchromic acid and one or more member selected from silica, phosphoricacid and hydrophilic resin, and drying the solution.

[0048] In the phosphate treatment, the amount of phosphate attached ispreferably from 0.5 to 3.5 g/m² as phosphate. In the chromate treatment,the amount of chromate attached is, in terms of metal chromium,preferably from 5 to 150 mg/m², more preferably from 10 to 50 mg/m². Ifthe amount attached is less than 5 mg/m², an effect of giving excellentcorrosion resistance cannot obtained, whereas if it exceeds 150 mg/m²,the chromate film undergoes cohesion failure during shaping and theworkability decreases. According to the purpose, the substrate may befurther subjected to an acid washing treatment, an alkali treatment, anelectrolytic reduction treatment, a cobalt plating treatment, a nickelplating treatment, a silane coupling agent treatment or an inorganicsilicate treatment.

[0049] In the present invention, the metal used is not particularlylimited and examples of the metal which can be used include aluminum,titanium, zinc, copper, nickel, an alloy containing such a metal, andsteel. In the case of using a steel, the components are not particularlylimited and either a common steel or a chromium-containing steel, suchas stainless steel, may be used. The shape of the steel product is alsonot limited and a steel sheet such as cold-rolled steel sheet andhotrolled steel sheet, a steel tube, a steel wire or the like can beused.

[0050] A covering plating layer may be present on the surface of a steeland the kind thereof is not limited but examples of the plating layerwhich can be used include a zinc-base plating layer such as zincplating, zinc-nickel plating, zinc-iron plating, zinc-chromium plating,zinc-aluminum plating, zinc-titanium plating, zinc-magnesium plating andzinc-manganese plating, an aluminum or aluminum alloy plating layer, alead or lead alloy plating layer, a tin or tin alloy plating layer, andthose plating layers where a small amount of one or more heteroelementsuch as cobalt, molybdenum, tungsten, nickel, titanium, chromium,aluminum, manganese, iron, magnesium, lead, antimony, tin, copper,cadmium and arsenic is contained or an inorganic material such assilica, alumina and titania is dispersed.

[0051] The present invention can also be applied to a multilayer platinglayer comprising a combination of the above-described plating andanother kind of plating such as iron plating and iron-phosphorusplating. The plating method is not particularly limited andelectroplating, hot dipping, vapor deposition plating and the like canbe used. In the case of a steel sheet, the treatment after platingincludes, for example, a zero spangling treatment which is an appearanceuniformalizing treatment after hot dipping, an annealing treatment whichis a treatment for reforming the plating layer, and temper-rolling foradjusting the surface state or material quality, however, in the presentinvention, the after-treatment is not particularly limited and any ofthese treatments can be applied.

[0052] In the metal product having formed thereon the lubricating filmof the present invention, a lubricating oil or a lubricating anti-rustoil can be further coated on the film. However, the lubricating oil orlubricating anti-rust oil coated is preferably an oil which does notswell or dissolve the lubricating film of the present invention.

[0053] The process of producing and using the alkali soluble lubricantsurface-treated metal product of the present invention is describedbelow by referring to FIGS. 1 to 3. An alkali-soluble lubricatingfilm-forming composition is coated on a steel sheet 1 to form alubricating film 2 (FIG. 1). The steel sheet 1 having formed thereon thelubricating film 2 is subjected, for example, to deep drawing andthereby a molded product 3 is obtained. This molded product comprises asteel sheet 4 and a lubricating film 5 and on the steel sheet 4, andscratching or galling is not observed (FIG. 2). After the shaping, themetal product 3 is treated with an alkali solution by a dipping methodor a spray method to remove the lubricating film 5 and obtain a metalproduct 4 as a final product (FIG. 3).

EXAMPLES

[0054] The present invention will be described, in greater detail below,by referring to Examples and Comparative Examples. However, the presentinvention is not limited to these Examples.

[0055] 1. Sample Metal Sheet

[0056] The following metal sheets were used as the metal sheet on whicha lubricating film is coated.

[0057] Zinc electroplated steel sheet (thickness: 0.8 mm, plated amount:20 g/m²)

[0058] Zinc-nickel alloy electroplated steel sheet (thickness: 0.8 mm,plated amount: 20 g/m²)

[0059] Zinc-iron alloy electroplated steel sheet (thickness: 0.8 mm,plated amount: 20 g/m²)

[0060] Zinc hot-dipped steel sheet (thickness: 0.8 mm, plated amount:150 g/m²)

[0061] Zinc-iron alloy hot-dipped steel sheet (thickness: 0.8 mm, platedamount: 45 g/m²)

[0062] Zinc-aluminum alloy hot-dipped steel sheet (thickness: 0.8 mm,plated amount: 150 g/m²)

[0063] Aluminum-silicon alloy hot-dipped steel sheet (thickness: 0.8 mm,plated amount: 50 g/m²)

[0064] Aluminum-silicon-magnesium alloy hot-dipped steel sheet(thickness: 0.8 mm, plated amount. 50 g/m²)

[0065] Stainless steel sheet (thickness: 0.8 mm, SUS 430, 2B finish)

[0066] Aluminum alloy sheet (thickness: 0.8 mm)

[0067] Cold-rolled steel sheet (thickness: 0.8 mm)

[0068] Of these metal sheets, in the case-of plated steel sheet, acoating-type chromate solution obtained by adding colloidal silica tochromic acid having a chromium reduction ratio of (Cr(VI)/entire Cr)=0.4was coated by a roll coater to have a chromium attached amount of 20mg/m² in terms of metal chromium, and dried under heating to form achromate film. In the case of stainless steel sheet, aluminum alloysheet and cold-rolled steel sheet, the chromate treatment was notapplied.

[0069] 2. Polyurethane Aqueous Composition

[0070] The alkali-soluble polyurethane aqueous compositions used wereprepared as follows.

Production Example 1

[0071] In a four-neck flask equipped with a stirrer, a Dimrothcondenser, a nitrogen inlet, a silica gel drying tube and a thermometer,87.11 g of 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate, 31.88g of 1,3-bis(1-isocyanato-1-methylethyl)benzene, 41.66 g ofdimethylolpropionic acid, 4.67 g of triethylene glycol, 62.17 g of apolyester polyol comprising adipic acid, neopentyl glycol and1,6-hexanediol and having a molecular weight of 2,000, and 122.50 g ofacetonitrile as the solvent were added and, after elevating thetemperature to 70° C., it was stirred for 4 hours in a nitrogenatmosphere. Then, it was confirmed that the solution reached apredetermined amine equivalent. Thus, an acetonitrile solution ofpolyurethane prepolymer was obtained. Subsequently, 346.71 g of theobtained polyurethane prepolymer solution was dispersed using ahomodisper in an aqueous solution obtained by dissolving 12.32 g ofsodium hydroxide in 639.12 g of water, and thereby formed into anemulsion. In this polyurethane emulsion, 12.32 g of2-[(2-aminoethyl)amino]ethanol diluted with 110.88 g of water was addedto perform a chain elongation reaction. Thereafter, acetonitrile used inthe synthesis of polyurethane prepolymer was removed by distillation at50° C. under a reduced pressure of 150 mmHg. As a result, a polyurethaneemulsion substantially free of a solvent and having an acid value of 69,a solid content concentration of 25 mass % and a viscosity of 30 mPa·s,was obtained.

Production Example 2

[0072] In a four-neck flask equipped with a stirrer, a Dimrothcondenser, a nitrogen inlet, a silica gel drying tube and a thermometer,132.49 g of 3-isocyanatomethyl3,5,5-trimethylcyclohexylisocyanate, 48.49g of 1,3-bis (1-isocyanato-1-methylethyl)benzene, 57.09 g ofdimethylolpropionic acid, 10.61 g of triethylene glycol, 141.31 g of apolyester polyol comprising adipic acid, neopentyl glycol and1,6-hexanediol and having a molecular weight of 2,000, and 210.00 g ofacetone as the solvent were added and, after elevating the temperatureto 50° C., it was stirred for 7 hours in a nitrogen atmosphere. Then, itwas confirmed that the solution reached a predetermined amineequivalent. Thus, an acetone solution of polyurethane prepolymer wasobtained. Subsequently, 485.97 g of the obtained polyurethane prepolymersolution was dispersed using a homodisper in an aqueous sodium hydroxidesolution obtained by dissolving 13.80 g of sodium hydroxide in 667.12 gof water, and thereby formed into an emulsion. In this polyurethaneemulsion, 15.32 g of 2-[(2-aminoethyl)amino]ethanol diluted with 137.88g of water was added to perform a chain elongation reaction. Thereafter,acetonitrile used in the synthesis of polyurethane prepolymer wasremoved by distillation at 50° C. under a reduced pressure of 150 mmHg.As a result, a polyurethane emulsion substantially free of a solvent andhaving an acid value of 56, a solid content concentration of 30 mass %and a viscosity of 100 mPa·s, was obtained.

Production Example 3

[0073] In a four-neck flask equipped with a stirrer, a Dimrothcondenser, a nitrogen inlet, a silica gel drying tube and a thermometer,120.69 g of 3-isocyanatomethyl3,5,5-trimethylcyclohexylisocyanate, 44.17g of 1,3- bis(1-isocyanato-l-methylethyl)benzene, 47.06 g ofdimethylolpropionic acid, 12.44 g of triethylene glycol, 165.65 g of apolyester polyol comprising adipic acid, neopentyl glycol and1,6-hexanediol and having a molecular weight of 2,000, and 210.00 g ofacetonitrile as the solvent were added and, after elevating thetemperature to 70° C., it was stirred for 5 hours in a nitrogenatmosphere. Then, it was confirmed that the solution reached apredetermined amine equivalent. Thus, an acetonitrile solution ofpolyurethane prepolymer was obtained. Subsequently, 491.37 g of theobtained polyurethane prepolymer solution was dispersed using ahomodisper in an aqueous sodium hydroxide solution obtained bydissolving 11.50 g of sodium hydroxide in 678.01 g of water, and therebyformed into an emulsion. In this polyurethane emulsion, 14.11 g of2-[(2aminoethyl)amino]ethanol diluted with 126.99 g of water was addedto perform a chain elongation reaction. Thereafter, acetonitrile used inthe synthesis of polyurethane prepolymer was removed by distillation at50° C. under a reduced pressure of 150 mmHg. As a result, a polyurethaneemulsion substantially free of a solvent and having an acid value of 47,a solid content concentration of 30 mass % and a viscosity of 35 mPa's,was obtained.

Production Example 4

[0074] In a four-neck flask equipped with a stirrer, a Dimrothcondenser, a nitrogen inlet, a silica gel drying tube and a thermometer,111.49 g of 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate,45.72 g of dimethylolbutyric acid, 192.8 g of a polyester polyolcomprising isophthalic acid, sebacic acid, neopentyl glycol and ethyleneglycol and having a molecular weight of 2,500, and 150.00 g ofacetonitrile as the solvent were added and, after elevating thetemperature to 70° C., it was stirred for 5 hours in a nitrogenatmosphere. Then, it was confirmed that the solution reached apredetermined amine equivalent. Thus, an acetonitrile solution ofpolyurethane prepolymer was obtained. Subsequently, 403.25 g of theobtained polyurethane prepolymer solution was dispersed using ahomodisper in an aqueous sodium hydroxide solution obtained bydissolving 9.95 g of sodium hydroxide in 630.07 g of water and, thereby,formed into an emulsion. In this polyurethane emulsion, 7.77 g of2-[(2-aminoethyl)amino]ethanol diluted with 69.93 g of water was addedto perform a chain elongation reaction. Thereafter, acetonitrile used inthe synthesis of polyurethane prepolymer was removed by distillation at50° C. under reduced pressure of 150 mmHg. As a result, a polyurethaneemulsion substantially free of a solvent and having an acid value of 47,a solid content concentration of 30 mass % and a viscosity of 15 mpa·s,was obtained.

Production Example 5

[0075] In a four-neck flask equipped with a stirrer, a Dimrothcondenser, a nitrogen inlet, a silica gel drying tube and a thermometer,20.35 g of 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate, 67.03g of 1,3-bis(1-isocyanato-l-methylethyl)benzene, 24.05 g ofdimethylolbutyric acid, 238.58 g of a polyester polyol comprising adipicacid, neopentyl glycol and 1,6hexanediol and having a molecular weightof 2,000, and 150.00 g of acetone as the solvent were added and afterelevating the temperature to 50° C., it was stirred for 7 hours in anitrogen atmosphere. Then, it was confirmed that the solution reached apredetermined amine equivalent. Thus, an acetone solution ofpolyurethane prepolymer was obtained. Subsequently, 393.45 g of theobtained polyurethane prepolymer solution was dispersed using ahomodisper in an aqueous triethanolamine solution obtained by dissolving19.05 g of triethanolamine in 650.14 g of water, and thereby formed intoan emulsion. In this polyurethane emulsion, 5.54 g of2-[(2-aminoethyl)amino]ethanol diluted with 49.86 g of water was addedto perform a chain elongation reaction. Thereafter, acetone used in thesynthesis of polyurethane prepolymer was removed by distillation at 50°C. under a reduced pressure of 150 mmHg. As a result, a polyurethaneemulsion substantially free of a solvent and having an acid value of24.0, a solid content concentration of 30 mass % and a viscosity of 50mPa's, was obtained.

[0076] 3. Lubricating Function-imparting Agent (Wax or Solid Lubricant)

[0077] The following waxes or lubricants were used as the lubricatingfunction-imparting agent.

[0078] PE wax A (low-density polyethylene wax, softening temperature:110° C., average particle size: 4.0 μm, dispersed as an aqueousemulsion, solid content: 40 mass %)

[0079] PE wax B (low-density polyethylene wax, softening temperature:110° C., average particle size: 1.0 μm, dispersed as an aqueousemulsion, solid content: 40 mass %)

[0080] PTFE wax (polytetrafluoroethylene wax, average particle size: 0.8μm, dispersed as an aqueous emulsion, solid content: 60 mass %)

[0081] Paraffin wax (synthetic paraffin wax, melting point: 105° C.,average particle size: 5.0 μm, dispersed as an aqueous emulsion, solidcontent: 33 mass %)

[0082] Calcium stearate (average particle size: 2.0 μm, dispersed as anaqueous emulsion, solid content: 40 mass %)

[0083] 4. Silica Particles

[0084] As the silica particles, colloidal silica having a particle sizeof 10 to 20 nm, a pH of 8.6 and a heating residue of about 20 mass % wasadded to a content of 10 mass % in the film.

[0085] 5. Production of Surface-lubricated Metal Product

EXAMPLE 1

[0086] Polyurethane aqueous composition 320 parts by weight (80 mass %in of Production Example 1 terms of solid content in film) PE Wax A 25parts by weight (10 mass % in terms of solid content in film) Colloidalsilica 50 parts by weight (10 mass % in terms of solid content in film)

[0087] A coating solution having the constitution shown above was coatedon a metal sheet by a bar coater and bake-dried at a metal sheetachievable temperature of 80° C. using a heating furnace at 180° C. toform a lubricating film, having a composition shown in Tables 1 and 2,on the metal sheet.

[0088] In order to confirm that a film comprising an alkali-solublepolyurethane aqueous composition (A) was formed on the metal sheet, aspectral identification corresponding to the urethane resin componentswas performed by the following FT-IR analysis (highly-sensitivereflection method and hydrofluoric acid-microscopic reflection method).

[0089] (1) Highly-sensitive Reflection Method

[0090] Nondestructive analysis. Resolution: 4 cm⁻¹, detector: TGS,incident beam: 13 mmφ, beam incident angle: 75° (with use of apolarizer), number of integrations: 100 times.

[0091] (2) Hydrofluoric Acid-microscopic Reflection Method

[0092] A surface-lubricated metal sheet of 1 cm×1 cm square was dippedin hydrofluoric acid and the free film after the elution of silicaportion was attached on a stainless steel sheet to prepare a testsample. Resolution: 4 cm⁻¹, detector: MCT, incident beam: 250 μm square,number of integrations: 500 times.

[0093] Whichever method was used, peaks appeared in the vicinity of1,540 m⁻¹ (ascribable to C—N stretching and N—H deformation vibration ofa urethane bond), in the vicinity of 1,650 m⁻¹ (ascribable to C═Ostretching of urea), in the vicinity of 1,730 m⁻¹ (ascribable to C=Ostretching of urethane bond) and in the vicinity of 3,330 m⁻¹(ascribable to N—H stretching of urethane bond). These are the wavenumbers characteristic of a polyurethane composition and therefore, itwas confirmed that the film contains the components of a polyurethanecomposition. TABLE 1 Amount of Kind of Wax or Solid Lubricant, Contentin Film Chromate Paraffin Calcium Attached PE Wax A PE Wax B PTFE WaxWax Stearate No. Species of Metal Sheet (mg/m²) Aqueous Composition(mass %) (mass %) (mass %) (mass %) (mass %)  1 Zinc electroplated steelsheet 20 Production Example 1 10  2 Zinc electroplated steel sheet 20Production Example 4 10  3 Zinc-nickel alloy electroplated 20 ProductionExample 1 10  4 steel sheet 20 Production Example 4 10  5 Zinc-ironalloy electroplated 20 Production Example 1 10 steel sheet  6 Zinc-ironalloy electroplated 20 Production Example 4 10 steel sheet  7 Zinchot-dipped steel sheet 20 Production Example 1 10  8 Zinc hot-dippedsteel sheet 20 Production Example 4 10  9 Zinc-iron alloy hot-dippedsteel 20 Production Example 1 10 sheet 10 Zinc-iron alloy hot-dippedsteel 20 Production Example 4 10 sheet 11 Zinc-aluminum alloy hot-dipped20 Production Example 1 10 12 steel sheet 20 Production Example 4 10 13Aluminum-silicon alloy hot-dipped 20 Production Example 1  3 14 steelsheet 20 Production Example 1 10 15 20 Production Example 1 25 16 20Production Example 1 10 17 20 Production Example 1 10 18 20 ProductionExample 1  5 19 20 Production Example 1 15 20 20 Production Example 1 1021 20 Production Example 1 10 22 20 Production Example 1 10 23 20Production Example 1 10 24 20 Production Example 2 10 25 20 ProductionExample 2 10 26 20 Production Example 3 10 27 20 Production Example 3 1028 20 Production Example 4 10 29 20 Production Example 4 10 30Aluminum-silicon-magnesium alloy 20 Production Example 1 10 hot-dippedsteel sheet 31 Stainless steel sheet not treated Production Example 1  332 Stainless steel sheet not treated Production Example 1 10 33Stainless steel sheet not treated Production Example 1 25 34 Stainlesssteel sheet not treated Production Example 1 10 35 Stainless steel sheetnot treated Production Example 1 10 36 Stainless steel sheet not treatedProduction Example 1 10 Generation of Elastic Resin Debris Silica FilmModulus Tensile Glass Mold Galling after Working Evaluation ofDegreasing Content Thick- after Elongation Transition Room RoomProperty, Film Residual in Film ness Coating Percentage TemperatureTemper- Temper- Ratio after Film Removal No. (mass %) (μm) (GPa) (%) (°C.) ature 100° C. ature 100° C. by Alkali Remarks  1 10 1.0 9.6 1% 139 ⊚⊚ ⊚ ⊚ ⊚ Example of  2 10 1.0 5.2 147%  133 ⊚ ⊚ ⊚ ⊚ ⊚ Invention  3 10 1.09.8 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚  4 10 1.0 5.4 147%  133 ⊚ ⊚ ⊚ ⊚ ⊚  5 10 1.0 9.2 1%139 ⊚ ⊚ ⊚ ⊚ ⊚  6 10 1.0 4.8 147%  133 ⊚ ⊚ ⊚ ⊚ ⊚  7 10 1.0 9.6 1% 139 ⊚ ⊚⊚ ⊚ ⊚  8 10 1.0 5.1 147%  133 ⊚ ⊚ ⊚ ⊚ ⊚  9 10 1.0 9.6 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚10 10 1.0 5.0 147%  133 ⊚ ⊚ ⊚ ⊚ ⊚ 11 10 1.0 9.1 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 12 101.0 4.4 147%  133 ⊚ ⊚ ⊚ ⊚ ⊚ 13 10 1.0 9.9 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 14 10 1.0 9.31% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 15 10 1.0 7.9 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 16 10 1.0 9.6 1% 139 ⊚ ⊚⊚ ⊚ ⊚ 17 10 1.0 9.5 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 18 10 1.0 8.9 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 1910 1.0 7.5 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 20 10 1.0 9.8 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 21 10 2.0 9.61% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 22 10 5.0 9.4 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 23 10 8.0 9.9 1% 139 ⊚ ⊚⊚ ⊚ ⊚ 24 10 2.0 6.5 7% 129 ⊚ ⊚ ⊚ ⊚ ⊚ 25 10 5.0 6.3 7% 129 ⊚ ⊚ ⊚ ⊚ ⊚ 2610 2.0 5.9 299%  121 ⊚ ⊚ ⊚ ⊚ ⊚ 27 10 5.0 5.4 299%  121 ⊚ ⊚ ⊚ ⊚ ⊚ 28 102.0 4.9 147%  133 ⊚ ⊚ ⊚ ⊚ ⊚ 29 10 5.0 4.7 147%  133 ⊚ ⊚ ⊚ ⊚ ⊚ 30 10 1.09.2 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 31 10 1.0 10.1 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 32 10 1.0 9.3 1%139 ⊚ ⊚ ⊚ ⊚ ⊚ 33 10 1.0 7.1 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 34 10 1.0 9.4 1% 139 ⊚ ⊚ ⊚⊚ ⊚ 35 10 1.0 9.4 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 36 10 1.0 9.2 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚

[0094] TABLE 2 Amount of Kind of Wax or Solid Lubricant, Content in FilmChromate Paraffin Calcium Attached PE Wax A PE Wax B PTFE Wax WaxStearate No. Species of Metal Sheet (mg/m²) Aqueous Composition (mass %)(mass %) (mass %) (mass %) (mass %) 37 Stainless steel sheet not treatedProduction Example 1 10 38 Stainless steel sheet not treated ProductionExample 1 10 39 Stainless steel sheet not treated Production Example 110 40 Stainless steel sheet not treated Production Example 1 10 41Stainless steel sheet not treated Production Example 2 10 42 Stainlesssteel sheet not treated Production Example 3 10 43 Stainless steel sheetnot treated Production Example 4 10 44 Aluminum alloy sheet not treatedProduction Example 1 10 45 Aluminum alloy sheet not treated ProductionExample 4 10 46 Cold-rolled steel sheet not treated Production Example 110 47 Cold-rolled steel sheet not treated Production Example 4 10 48Aluminum-silicon alloy hot-dipped 20 Production Example 1 0.7 49 steelsheet 20 Production Example 1 35 50 20 Production Example 1 10 51 20Production Example 4 0.7 52 20 Production Example 4 35 53 20 ProductionExample 4 10 54 20 acrylic resin 10 55 20 10 56 20 Production Example 510 57 20 Production Example 5 10 58 Stainless steel sheet not treatedProduction Example 1 0.7 59 Stainless steel sheet not treated ProductionExample 1 35 60 Stainless steel sheet not treated Production Example 110 61 Stainless steel sheet not treated acrylic resin 10 62 Stainlesssteel sheet not treated 10 63 Stainless steel sheet not treatedProduction Example 5 10 64 Stainless steel sheet not treated ProductionExample 5 10 65 Cold-rolled steel sheet not treated Production Example 110 Generation of Elastic Resin Debris Silica Film Modulus Tensile GlassMold Galling after Working Evaluation of Degreasing Content Thick- afterElongation Transition Room Room Property, Film Residual in Film nessCoating Percentage Temperature Temper- Temper- Ratio after Film RemovalNo. (mass %) (μm) (GPa) (%) (° C.) ature 100° C. ature 100° C. by AlkaliRemarks 37 10 1.0 9.5 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ Example of 38 10 0.5 9.2 1% 139 ⊚⊚ ⊚ ⊚ ⊚ Invention 39 10 2.0 9.3 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 40 10 5.0 9.6 1% 139 ⊚⊚ ⊚ ⊚ ⊚ 41 10 1.0 6.6 7% 129 ⊚ ⊚ ⊚ ⊚ ⊚ 42 10 1.0 5.2 299%  121 ⊚ ⊚ ⊚ ⊚ ⊚43 10 1.0 5.0 147%  133 ⊚ ⊚ ⊚ ⊚ ⊚ 44 10 1.0 9.9 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 45 101.0 4.9 147%  133 ⊚ ⊚ ⊚ ⊚ ⊚ 46 10 1.0 9.2 1% 139 ⊚ ⊚ ⊚ ⊚ ⊚ 47 10 1.0 5.5147%  133 ⊚ ⊚ ⊚ ⊚ ⊚ 48 10 1.0 9.9 1% 139 Δ X Δ X ⊚ Comparison 49 10 1.03.9 1% 139 ⊚ ◯ X X ⊚ 50 10 0.25 9.2 1% 139 X X ◯ Δ ⊚ 51 10 1.0 4.8 147% 133 Δ X Δ X ⊚ 52 10 1.0 2.2 147%  133 ◯ ◯ X X ⊚ 53 10 0.25 5.1 147%  133X X ◯ Δ ⊚ 54 10 1.0 2.4 14%   85 Δ X Δ X ⊚ 55 10 2.0 2.6 14%   85 X X ΔΔ ◯ 56 10 1.0 0.3 1125%    55 X X Δ X ⊚ 57 10 3.0 0.3 1125%    55 X X ΔΔ ⊚ 58 10 1.0 9.5 1% 139 Δ Δ Δ Δ ◯ 59 10 1.0 9.8 1% 139 ⊚ ◯ ◯ Δ ⊚ 60 100.25 9.2 1% 139 X X ◯ ◯ ⊚ 61 10 1.0 2.2 14%   85 Δ X Δ X ◯ 62 10 2.0 2.614%   85 X X Δ Δ ◯ 63 10 1.0 0.4 1125%    55 X X Δ X ⊚ 64 10 3.0 0.41125%    55 X X Δ X ◯ 65 10 0.25 10.0 1% 139 Δ X ◯ Δ ⊚

Examples 2 to 47 and Comparative Examples 48 to 65

[0095] Surface-lubricated metal sheets were produced in the same manneras in Example 1 by baking a lubricating film having a composition shownin Tables 1 and 2 (Example Nos. 2 to 47 and Comparative Example Nos. 48to 65) on each metal sheet. Here, similarly to Example 1, it wasconfirmed by FT-IR analysis that a polyurethane composition is containedin the film. Using an alkali-soluble acrylic aqueous composition as acomparative material of the polyurethane aqueous composition, the filmformation was performed in the same manner (Comparative Example Nos. 54,55, 61 and 62).

[0096] 6. Test and Evaluation Methods

[0097] The surface-lubricated metal sheets produced above were evaluatedon the following performances.

[0098] (1) Measurement of Elastic Modulus after Coating

[0099] The elastic modulus of film after coating on a metal surface wasdetermined under the following conditions using an ultrafine hardnesstesting machine “FISHER SCOPE H-100” manufactured by Fisher InstrumentCo. This measurement can be performed not only by this device but alsoby other similar general-purpose devices. Indenter:

[0100] Vickers quadrangular pyramid-shaped diamond indenter Measurementtemperature: 25° C.

[0101] Maximum Penetration Depth of Indenter:

[0102] ½ or less of film thickness; in order to eliminate the effect ofmetal surface far harder than film, the press fitting (increase of load)was stopped in the depth range where the gradient of a graph configuredby the square root (F½) of applied load F and the penetration depth hbecomes constant [d(F½)/dh=constant], and subsequently, the load wasdecreased.

[0103] Applied Load Increasing Mode:

[0104] The load was stepwise increased every 1.0, 2.0 or 4.0 seconds.With the square root (F½) of applied load F and the elapsed time t,d(F½)/dt=constant. In order to reduce the effect of film creep, the loadapplication time was set to 4 seconds at the longest.

[0105] Applied Load Decreasing Mode:

[0106] The load was stepwise decreased every 1.0, 2.0 or 4.0 seconds.With the square root (F½) of applied load F and the elapsed time t,d(F½)/dt=constant.

[0107] (2) Measurement of Tensile Elongation Percentage

[0108] The tensile elongation percentage of the alkali-solublepolyurethane aqueous composition as the main component of thelubricating film was determined under the following conditions usingSTROGRAPH R manufactured Toyo Seiki Seisaku-Sho, Ltd. This measurementcan be performed not only by this device but also by using a generaltensile tester made by another company.

[0109] Sample:

[0110] An emulsion solution of alkali-soluble polyurethane aqueouscomposition was cast on a clean glass plate, air-dried and then driedunder heating for about 1 hour in an oven set at 100° C. to form a thinfilm having a uniform film thickness (film thickness range: 10 to 200μm), and a thin film specimen in a width of 10 mm was cut out while notcausing cracks or flaws at the end part and used as the sample.

[0111] Measurement Conditions:

[0112] Measurement temperature: 25° C., chuck-to-chuck distance: 10 mm,pulling rate: 5 mm/min.

[0113] The tensile elongation percentage of the alkali-solublepolyurethane aqueous composition constituting the surface-treating filmof the alkali soluble lubricant surface-treated metal product may bemeasured as follows. An alkali-soluble surface-lubricating film isdissolved from a surface-treated metal product to remove solid matterssuch as lubricating function-imparting agent and silica and therebyseparate the alkali-soluble polyurethane aqueous composition, then athin film of the alkali-soluble polyurethane aqueous composition isformed in the same manner as above, and the tensile elongationpercentage thereof is measured.

[0114] (3) Measurement of Glass Transition Temperature

[0115] The glass transition temperature of the polyurethane aqueouscomposition in the lubricating film was determined from the peak on aDSC curve obtained under the following conditions using a differentialscanning calorimeter (DSC-6200R) manufactured by Seiko Instruments Inc.This can also be measured by using a general-purpose device made byanother company.

[0116] Sample:

[0117] The lubricating film powder scraped off from the surface of thesurface-lubricated metal sheet was placed in an aluminum sample dish andused as the sample.

[0118] Measurement Conditions:

[0119] The measurement was performed from room temperature to 230° C. ata temperature-rising rate of 5.0° C./min in a dry nitrogen flowatmosphere.

[0120] (4) Evaluation of Mold Galling

[0121] A shaping test was performed under the following conditions usinga hydraulic shaping tester with a cylindrical punch. As for thetemperature conditions in the shaping test, the evaluation was performedat the two levels of room temperature and a mold temperature (100° C.)elevated due to continuous pressing. Punch diameter: 70 mmφ Blankdiameter: 150 mmφ Pressing load: 5 kgf/cm² Shaping rate: 3.3 × 10⁻² m/sTool condition: FCD-500

[0122] In all cases, the steel sheet was shaped to 80% of the maximumshaping height and the mold galling was evaluated according to thefollowing indices.

[0123] ⊚: The steel sheet could be shaped and the surface was free ofdefects.

[0124] ◯The steel sheet could be shaped and the surface was free ofdefects but the sliding surface was slightly discolored.

[0125] Δ: The steel sheet could be shaped but a galling flaw wasslightly generated on the surface.

[0126] X: The steel sheet could be shaped but a large number of lineargalling flaws were generated on the surface.

[0127] Also, the generation of resin debris after working was evaluatedaccording to the following indices.

[0128] ⊚: Debris was not generated.

[0129] ◯: Trace resin debris was generated.

[0130] Δ: Resin debris was slightly generated.

[0131] X: A large amount of resin debris was generated.

[0132] (5) Evaluation of Degreasing Property

[0133] The test piece was sprayed with a degreasing solution FC-4358(produced by Nihon Parkerizing Co., Ltd., pH: adjusted to 0.5, liquidtemperature: 40° C.) for 8 seconds, then washed with water and dried andthereafter, the film residual ratio was measured by infraredspectroscopic analysis and evaluated.

[0134] ⊚: No film.

[0135] ◯: The film residual area percentage is 5% or less.

[0136] Δ: The film residual area percentage is more than 5% to 10%.

[0137] X: The film residual area percentage is more than 10%.

[0138] The tensile elongation percentage of the aqueous composition was1% in the case of Production Example 1, 7% in the case of ProductionExample 2, 299% in the case of Production Example 3, 147% in the case ofProduction Example 4, 1,125% in the case of Production Example 5, and14% in the case of acrylic resin.

[0139] As seen from Tables 1 and 2, the surface-lubricated metal productaccording to the present invention exhibits excellent shapability inboth cases of room temperature and a mold temperature (100° C.) elevateddue to continuous pressing, generates less debris after shaping andensures good film removal by the alkali degreasing. On the other hand,when the aqueous composition, the amount of wax added, the filmthickness and the elastic modulus after coating are each out of therange specified in the present invention, poor shapability results andresin debris is readily generated after shaping.

[0140] Industrial Applicability

[0141] The metal product of the present invention is free of moldgalling even under severe shaping conditions and is deprived of thelubricating film after degreasing and therefore, is suitably used foruses where the glossy metal surface or a metal texture is required or agood welding property is demanded. Thus, the present invention has avery high industrial value.

1. A surface-lubricated metal product with excellent shapability,comprising a metal having coated on both surfaces or on one surfacethereof an alkali-soluble lubricating film mainly comprising (A) analkali-soluble polyurethane aqueous composition containing a carboxylgroup or a sulfonic acid group within the molecule and (B) a lubricatingfunction-imparting agent in an amount of 1 to 30 mass % based on saidalkali-soluble polyurethane aqueous composition, said film being coatedto have a film thickness of 0.5 to 10 μm and the elastic modulus of saidfilm after coating being 0.5 to 20 GPa at 25° C.
 2. Thesurface-lubricated metal product with excellent shapability as claimedin claim 1, wherein the alkali-soluble lubricating film mainly comprises(A) an alkali-soluble polyurethane aqueous composition, (B) alubricating function-imparting agent in an amount of 1 to 30 mass %based on said alkali-soluble polyurethane aqueous composition and (c)silica particles in an amount of 1 to 30 mass % based on said alkalisoluble polyurethane aqueous composition.
 3. The surface-lubricatedmetal product with excellent shapability as claimed in claim 1 or 2,wherein the amount of the acid radical contained in the alkali-solublepolyurethane aqueous composition (A) constituting the alkali-solublelubricating film is from 30 to 180 in terms of the acid value.
 4. Thesurface-lubricated metal product with excellent shapability as claimedin claim 1 or 2, wherein a neutralizer for the acid radical contained inthe alkali-soluble polyurethane aqueous composition (A) constituting thealkali-soluble lubricating film is sodium hydroxide or potassiumhydroxide.
 5. The surface-lubricated metal product with excellentshapability as claimed in any one of claims 1 to 4, wherein the maincomponent of the alkali-soluble polyurethane aqueous composition (A)constituting the alkali-soluble lubricating film is a polyester polyol.6. The surface-lubricated metal product with excellent shapability asclaimed in any one of claims 1 to 5, wherein the lubricatingfunction-imparting agent (B) comprises one or more member selected fromthe group consisting of a polyolefin-base wax, a paraffin-base wax, astearic acid-base solid lubricant and a wax comprising afluorine-containing resin.
 7. The surface-lubricated metal product withexcellent shapability as claimed in any one of claims 1 to 6, whereinthe elastic modulus of said film after coating is 0.5 to 6 GPa at 25° C.and, at the same time, the tensile elongation percentage of thealkali-soluble polyurethane aqueous composition (A) as the maincomponent of said film exceeds 10%, or, the elastic modulus of said filmafter coating exceeds 6 GPa at 25° C. and, at the same time, the tensileelongation percentage of the alkali-soluble polyurethane aqueouscomposition (A) as the main component of said film, is 10% or less. 8.The surface-lubricated metal product with excellent shapability asclaimed in any one of claims 1 to 7, wherein the glass transitiontemperature of the alkali-soluble polyurethane aqueous composition (A)in the coated lubricating film is 100° C. or more.
 9. Asurface-lubricated metal product with excellent shapability, comprisinga metal having coated on both surfaces or one surface thereof analkali-soluble lubricating film mainly comprising (A) an alkali-solublepolyurethane aqueous composition containing a carboxyl group or asulfonic acid group within the molecule and (B) a lubricatingfunction-imparting agent in an amount of 1 to 30 mass % based on saidalkali-soluble polyurethane aqueous composition, the main component ofthe alkali-soluble polyurethane aqueous composition being a polyesterpolyol, a neutralizer for the acid radical contained in thealkali-soluble polyurethane aqueous composition (A) being sodiumhydroxide or potassium hydroxide, the amount of the acid radicalcontained in the alkali-soluble polyurethane aqueous composition (A)being from 30 to 180 in terms of the acid value, the lubricatingfunction-imparting agent (B) comprising one or more member selected fromthe group consisting of a polyolefin-base wax, a paraffin-base wax, astearic acid-base solid lubricant and a wax comprising afluorine-containing resin, the alkali-soluble lubricating film beingcoated to have a film thickness of 0.5 to 10 82 m. the elastic modulusof said film after coating being 0.5 to 6 GPa at 25° C. and, at the sametime, the tensile elongation percentage of the alkali-solublepolyurethane aqueous composition (A) as the main component of said filmexceeding 10%, or the elastic modulus of said film after coatingexceeding 6 GPa at 25° C. and, at the same time, the tensile elongationpercentage of the alkali-soluble polyurethane aqueous composition (A) asthe main component of said film being 10% or less, and the glasstransition temperature of the alkali-soluble polyurethane aqueouscomposition (A) being 100° C. or more.
 10. The surface-lubricated metalproduct with excellent shapability as claimed in claim 9, which furthercomprises (C) silica particles in an amount of 1 to 30 mass % based onthe alkali-soluble polyurethane aqueous composition.